This invention relates to a protective enclosure for a backflow prevention device, and more particularly to a prefabricated insulated, protective enclosure for a backflow prevention device.
A backflow prevention device is an assembly of one or more check valves incorporated in a liquid supply line to prevent the backflow of any of the liquid, and particularly contaminated liquid, into the original uncontaminated supply line. Since these backflow prevention devices are usually installed in a water supply line outdoors and above ground, it is important that the devices be enclosed and protected from the weather, and particularly from freezing.
Heretofore, large concrete or cast iron boxes have been constructed around the backflow prevention device. A cover member or door is provided in the top of the box to provide the only access into the interior of the box for servicing the device. Open drain holes are formed in the lower portions of the side or end walls of the box to drain any water collecting within the box away from the box. Occasionally loose insulation material is placed within the box in an attempt to insulate the backflow prevention device.
Because of the size of the backflow prevention devices and the boxes, the top cover or door renders access within the interior of the box difficult.
Furthermore, because of the open fixed drain holes in the concrete or iron boxes, it is just as easy for water or other foreign objects to move from the outside through the drain holes into the interior of the box as it is for water to discharge through the drain holes. Furthermore, cold air can easily pass into the interior of the box through the drain holes, which can hasten the freezing of the water within the pipes and valves of the backflow prevention device.
Another cover device for partially enclosing a backflow prevention device is disclosed in the Devine U.S. Pat. No. 4,726,394 issued Feb. 23, 1988, for "HEATED COVER FOR PIPELINE BACKFLOW PREVENTER COMPONENT ASSEMBLY". This cover member includes several side sections including segments of the top wall adapted to be joined along certain longitudinal and transverse lines and clamped together on opposite sides of the backflow prevention device. The Devine cover member includes openings 44 in the top portion of the cover member to permit the valve stems 24 to project upward above the top of the cover member. The valve stems 24 support hand wheels 25 located above and on the outside of the cover member to facilitate controlling the valves from the outside of the cover member. The walls of the Devine cover member are insulated, and a drain opening 40 is provided in the end walls to permit drainage of liquid from the space within the cover member to the outside. The drain openings 40 are covered by flexible flaps 42 which will flex outwardly to permit to flow outwardly.
In spite of the coverage provided by the Devine cover member, nevertheless, the stem openings 44 provide passages for air into the cover chamber, and the stems 24 function as heat conducters permitting heat loss from the backflow prevention device to the outside of the cover member.